Disclosed herein is a liquid composition for promoting plant growth containing titanium dioxide nanoparticles. The liquid composition contains, as an active ingredient, an aqueous solution prepared by adjusting the pH of colloidal titanium dioxide, a plant growth promoting component, to 0.4-0.6, in order to prevent rapid precipitation of the colloidal titanium dioxide, and then diluting the colloidal titanium dioxide with water to a predetermined concentration. The colloidal titanium dioxide, an environmentally friendly substance harmless to plants and the human body, which is contained in the plant growth promoting composition, is prevented from rapidly precipitating when it is diluted for application to plants. The plant growth promoting composition is harmless to organisms, reduces environmental contamination caused by over-application of biochemical fertilizers and is inexpensive, leading to an increase in farmer's income.
